Cleaning robot capable of detecting 2d depth information and operating method thereof

ABSTRACT

There is provided a cleaning robot including a light source module, an image sensor and a processor. The light source module projects a line pattern and a speckle pattern toward a moving direction. The image sensor captures an image of the line pattern and an image of the speckle pattern. The processor calculates one-dimensional depth information according to the image of the line pattern and calculates two-dimensional depth information according to the image of the speckle pattern.

BACKGROUND 1. Field of the Disclosure

This disclosure generally relates to an electronic device capable ofdetecting depth information and, more particularly, to a cleaning robotcapable of detecting two-dimensional depth information and calculating awall distance, and an operating method of the cleaning robot.

2. Description of the Related Art

Nowadays, a trend is irreversible in factory to replace human workers bymachines. Even at home, because one can have more free time by usingrobots to do homework, various types of family robots are also createdduring which the cleaning robot is most well-known and popular.

The cleaning robot has sensors for detecting obstacles in front.However, the conventional cleaning robot can only detect one-dimensionaldepth information but is unable to identify the appearance of theobstacles.

In addition, the cleaning robot is also required to be able to calculatea wall distance when cleaning along a wall so as to efficiently cleancorners. The conventional cleaning robot adopts multiple differentsensors to respectively detect the front distance and the wall distance.However, field of views between said different sensors general have deadzones unable to detect any obstacle such that the conventional cleaningrobot frequently bumps to different obstacles during operation. Not onlygenerating noises, the bumping can further cause damages to furnitureand the robot itself to shorten the service lifetime thereof.

Accordingly, it is necessary to provide a cleaning robot capable ofcalculating both one-dimensional and two-dimensional depth informationaccording to images captured by an image sensor, and further calculatinga distance from a side wall accordingly.

SUMMARY

The present disclosure provides a cleaning robot capable of detectingtwo-dimensional depth information, and an operating method of thecleaning robot.

The present disclosure further provides a cleaning robot capable ofdetecting a front obstacle and a distance from a side wall by using asame image sensor, and an operating method of the cleaning robot.

The present disclosure further provides a cleaning robot capable ofdetecting a distance from a transparent obstacle.

The present disclosure provides a cleaning robot including a firstdiffractive optical element, a first light source, a second diffractiveoptical element, a second light source and an image sensor. The firstlight source is configured to project a line pattern through the firstdiffractive optical element. The second light source is configured toproject a speckle pattern through the second diffractive opticalelement. The image sensor is configured to acquire an image of the linepattern and an image of the speckle pattern.

The present disclosure further provides a cleaning robot including afirst diffractive optical element, a first light source, a first imagesensor, a second diffractive optical element, a second light source anda second image sensor. The first light source is configured to project aline pattern through the first diffractive optical element. The firstimage sensor is configured to capture an image of the line pattern. Thesecond light source is configured to project a speckle pattern throughthe second diffractive optical element. The second image sensor isconfigured to capture an image of the speckle pattern.

The present disclosure further provides an operating method of acleaning robot. The cleaning robot includes a light source, adiffractive optical element, an image sensor and a processor. The lightsource projects a line pattern through the diffractive optical element.The operating method includes the steps of: projecting a line patterntoward a first direction when the cleaning robot moves toward anobstacle; calculating, by the processor, a relative distance from theobstacle according to a first image of the line pattern captured by theimage sensor; controlling, by the processor, the cleaning robot to turnto move parallel to the obstacle when the relative distance is identicalto a predetermined distance; projecting the line pattern toward a seconddirection when the cleaning robot moves parallel to the obstacle; andmaintaining, by the processor, a parallel distance between the cleaningrobot and the obstacle to the predetermined distance according to asecond image of the line pattern captured by the image sensor.

The present disclosure further provides a cleaning robot including adiffractive optical element, a laser light source, a light emittingdiode, an image sensor and a processor. The laser light source isconfigured to project a line pattern toward a moving direction throughthe diffractive optical element. The light emitting diode is configuredto illuminate light with an emission angle toward the moving direction.The image sensor is configured to acquire an image with a field of viewtoward the moving direction. The processor is configured to controllighting of the laser light source and the light emitting diode, whereinwhen identifying that a signal-to-noise ratio of the image containingthe line pattern exceeds a threshold range, the processor is configuredto identify a distance of an obstacle according to an area of a brightregion in the image which is acquired when the light emitting diode islighting.

The present disclosure further provides a cleaning robot including alight source module and an image sensor. The light source module isconfigured to provide a line pattern and a speckle pattern. The imagesensor is configured to acquire an image of the line pattern and animage of the speckle pattern.

In the cleaning robot and the operating method of the presentdisclosure, according to different applications, the line pattern andthe speckle pattern are overlapped or not overlapped with each other,and the line pattern and the speckle pattern are generatedsimultaneously or sequentially.

In the cleaning robot and the operating method of the presentdisclosure, according to different applications, the light source moduleemits light of a single dominant wavelength to generate the line patternand the speckle pattern, or the light source module emits light ofdifferent dominant wavelengths to respectively generate the line patternand the speckle pattern.

In the cleaning robot and the operating method of the presentdisclosure, the image sensor includes a linear pixel array. Theprocessor controls the cleaning robot to move in a direction parallel toan obstacle at a substantially fixed wall distance according to an imagesize of the obstacle captured by the linear pixel array.

In the cleaning robot and the operating method of the presentdisclosure, the image sensor includes a wide-angle lens to allow a fieldof view of the image sensor to be larger than a diameter of the cleaningrobot. Accordingly, when the cleaning robot operates in a directionparallel to a wall, the image sensor still can continuous detect animage of the side wall to identify whether a wall distance is changed.Therefore, the cleaning robot of the present disclosure needs not toadopt another sensor to detect the wall distance, and the problem ofunable to detect dead zones is eliminated.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, advantages, and novel features of the present disclosurewill become more apparent from the following detailed description whentaken in conjunction with the accompanying drawings.

FIG. 1 is a schematic block diagram of a cleaning robot according to oneembodiment of the present disclosure.

FIG. 2 is an operational schematic diagram of a cleaning robot accordingto one embodiment of the present disclosure.

FIG. 3 is a schematic diagram of a pattern arrangement projected by acleaning robot according to one embodiment of the present disclosure.

FIGS. 4A-4C are timing diagrams of projecting two different patterns bya cleaning robot according to one embodiment of the present disclosure.

FIG. 5 is a flow chart of an operating method of a cleaning robotaccording to one embodiment of the present disclosure.

FIGS. 6A-6B are operational schematic diagrams of a cleaning robotaccording to one embodiment of the present disclosure.

FIG. 7 is another operational schematic diagram of a cleaning robotaccording to one embodiment of the present disclosure.

FIG. 8 is an operational schematic diagram of a cleaning robot accordingto an alternative embodiment of the present disclosure.

FIG. 9 is a schematic diagram of a bright region in an image associatedwith a light emitting diode captured by an image sensor in FIG. 8.

FIGS. 10A-10B are timing diagrams of lighting different light sources ofthe cleaning robot in FIG. 8.

DETAILED DESCRIPTION OF THE EMBODIMENT

It should be noted that, wherever possible, the same reference numberswill be used throughout the drawings to refer to the same or like parts.

Referring to FIG. 1, it is a schematic block diagram of a cleaning robot100 according to one embodiment of the present disclosure. The cleaningrobot 100 is used to clean a work surface S (e.g., a floor) by operatingon the work surface S. The cleaning method can use the conventionalmethod, and details thereof are not described herein.

The cleaning robot 100 of the present disclosure includes a light sourcemodule 11, an image sensor 13 and a processor 15 electrically coupled tothe light source module 1 land the image sensor 13. The light sourcemodule 11 includes at least one active light source, and is used toprovide or project a line pattern T1 and a speckle pattern T2 toward afront of a moving direction (e.g., the right of FIG. 1) of the cleaningrobot 100. In one non-limiting embodiment, the line pattern T1 isprojected downward on the work surface S and the speckle pattern T2 isprojected in a front direction, but the present disclosure is notlimited thereto. As long as the line pattern T1 is projected with a tiltangle (i.e. not parallel to the work surface S), the processor 15 isable to calculate a relative distance from the projected object by usingtriangulation method. More specifically, in the present disclosure, aprojected angle of the line pattern T1 is different from a projectedangle of the speckle pattern T2.

Referring to FIG. 2, it is an operational schematic diagram of acleaning robot 100 according to one embodiment of the presentdisclosure. In this embodiment, the light source module 11 includes atleast one coherent light source (e.g., a laser diode) or a partiallycoherent light source, and at least one diffractive optical element(DOE) 113 used to generate a line pattern T1 and a speckle pattern T2.For example, FIG. 2 shows that the diffractive optical element 113 iscomposed of a first diffractive optical element 113 _(T1) and a seconddiffractive optical element 113 _(T2).

FIG. 2 shows that the light source module 11 includes a first lightsource LD1, the first diffractive optical element 113 _(T1), a secondlight source LD2 and the second diffractive optical element 113 _(T2).In one non-limiting embodiment, the first diffractive optical element113 _(T1) and the second diffractive optical element 113 _(T2) arecombined together (e.g., by glue) to form a module to be easily arrangedin front of the light source. In other arrangement, the firstdiffractive optical element 113 _(T1) and the second diffractive opticalelement 113 _(T2) are disposed at different positions.

The first light source LD1 is arranged opposite to the first diffractiveoptical element 113 _(T1) and used to emit light to pass through thefirst diffractive optical element 113 _(T1) to project a line pattern T1in front of a moving direction of the cleaning robot 100. The secondlight source LD2 is arranged opposite to the second diffractive opticalelement 113 _(T2) and used to emit light to pass through the seconddiffractive optical element 113 _(T2) to project a speckle pattern T2 infront of the moving direction of the cleaning robot 100, wherein sizesand shapes of the speckles in the speckle pattern are not particularlylimited as long as a plurality of speckles of identical or differentshapes are generated on a projected surface.

FIG. 2 shows that the cleaning robot 100 includes a single image sensor13 which has a field of view FOV covering regions of the line pattern T1and the speckle pattern T2. The image sensor 13 is a CMOS image sensor,a CCD image sensor or other elements capable of detecting light energyand generating electrical signals. The image sensor 13 is used tocapture and acquire an image of the line pattern T1 and an image of thespeckle pattern T2, and then send the captured images to the processor15 for post-processing, e.g., identifying the distance (so called depth)and the shape (so called two-dimensional depth information) of theobstacle.

In FIG. 2, although the line pattern T1 is shown to be formed outside ofa region of the speckle pattern T2, the present disclosure is notlimited thereto. In FIG. 3, the line pattern T1 is shown to be formedwithin a region of the speckle pattern T2. In FIGS. 2 and 3, thepositional relationship and the scale ratio between the line pattern T1and the speckle pattern T2 are only intended to illustrate but not tolimit the present disclosure. It is possible to form the line pattern T1at the upper side, left side or right side of the speckle pattern T2 aslong as they are detectable by the image sensor 13.

Referring to FIGS. 4A-4C, they are timing diagrams of two differentpatterns T1 and T2 projected by the cleaning robot 100 of the presentdisclosure.

When the line pattern T1 and the speckle pattern T2 are overlapped witheach other as shown in FIG. 3, in one embodiment the first light sourceLD1 and the second light source LD2 are turned on sequentially (as shownin FIG. 4B) to respectively generate the line pattern T1 and the specklepattern T2 at different time points. In this embodiment, as the lightsources are lighted separately, the line pattern T1 and the specklepattern T2 do not interfere with each other, and thus the first lightsource LD1 and the second light source LD2 have identical or differentdominant wavelengths without particular limitations.

In another embodiment, the line pattern T1 and the speckle pattern T2are overlapped with each other and the first light source LD1 and thesecond light source LD2 are turned on simultaneously (as shown in FIG.4A). In order to allow the line pattern T1 and the speckle pattern T4 tonot interfere with each other, preferably a dominate wavelength of thefirst light source LD1 is different from a dominant wavelength of thesecond light source LD2. In this case, a part of pixels of the imagesensor 13 are covered by a light filter for detecting the line patternT1, and the other part of pixels are covered by another light filter fordetecting the speckle patter T2. The method for forming light filters onpixels is known to the art, and thus details thereof are not describedherein.

In the embodiment of FIG. 2, as the line pattern T1 and the specklepattern T2 are not overlapped, they do not interfere with each other.Accordingly, the first light source LD1 and the second light source LD2are arranged, according to different applications, to be turned onsimultaneously or sequentially, and have identical or different dominantwavelengths.

The processor 15 is, for example, a digital signal processor (DSP), amicrocontroller unit (MCU), a central processing unit (CPU) or anapplication specific integrated circuit (ASIC) that identify, bysoftware and/or hardware, whether there is an obstacle (e.g., wall,table legs, chair legs or lower part of other furniture or homeappliances) according to an image containing the line pattern T1, andidentify the appearance (referred to two-dimensional depth information)of the obstacle according to an image containing the speckle pattern T2.

For example referring to FIG. 2, if there is no obstacle within the FOVof the image sensor 13, a line section in the image of the line patternT1 captured by the image sensor 13 is a horizontal line at a positionP1.

When an obstacle smaller than a range of the FOV exists within the FOV,a part of the line section in the image of the line pattern T1 appearsat a different height (i.e. not at the position P1). Accordingly, theprocessor 15 identifies that there is an obstacle in front according toline sections at different positions.

When an obstacle larger than a range of the FOV exists within the FOV,the whole of the line section in the image of the line patter T1 appearsat a different height, e.g., moving upward or downward from the positionP1 which is determined according to relative positions between the lightsource module 11 and the image sensor 13. Accordingly, the processor 15identifies that there is an obstacle in front according to a positionshifting of the line section. In addition, the processor 15 furtheridentifies a distance from the obstacle according to the height (or ashifting amount) of the line section in the image of the line patternT1. For example, the cleaning robot 100 further includes a memory forstoring a relationship between positions of the line section anddistances from the obstacle (e.g., forming a look up table, LUT). Whenidentifying a position of the line section in the image of the linepattern T1, the processor 15 compares the calculated position with thestored information to obtain a distance of the obstacle (also adaptableto the case that a part of the line section appears at differentpositions).

To reduce the consumption power and increase the accuracy, when theprocessor 15 identifies no obstacle in the image of the line pattern T1,preferably only the first light source LD1 is turned on but the secondlight source LD2 is not turned on. For example, FIG. 4C shows that theprocessor 15 does not detect an obstacle at a first time t1, and thusonly the first light source LD1 is turned on at a second time t2. Whenan obstacle is detected at the second time t2, the second light sourceLD2 is turned on at a third time t3 (the first light source LD1 beingturned on optionally) to cause the image sensor 13 to acquire an imageof the speckle pattern T2. The processor 15 then identifies anappearance of the obstacle according to the image of the speckle patternT2. For example, the processor 15 calculates the appearance of theobstacle as two-dimensional depth information according to the variationof sizes and shapes of speckles on a surface of the obstacle, e.g., bycomparing with the stored information. The two-dimensional depthinformation is used as data for avoiding bumping an object andconstructing a map of the cleaned area.

In the above embodiment, a cleaning robot 100 having only one imagesensor 13 is taken as an example to illustrate the present disclosure,and the image sensor 13 captures images of both the line pattern T1 andthe speckle pattern T2. In another non-limiting embodiment, the cleaningrobot 100 includes a first image sensor for capturing an image of theline pattern T1 and a second image sensor for capturing an image of thespeckle pattern T2 to reduce the interference therebetween. In thisembodiment, arrangements of the first light source LD1, the firstdiffractive optical element 113 _(T1), the second light source LD2 andthe second diffractive optical element 113 _(T2) are not changed, andthus details thereof are not repeated herein.

The first image sensor and the second image sensor acquire imagesrespectively corresponding to operations of the first light source LD1and the second light source LD2. For example, the first light source LD1and the second light source LD2 emit light sequentially, and the firstimage sensor and the second image sensor respectively capture images ofthe line pattern T1 and the speckle patter T2 corresponding to thelighting of the first light source LD1 and the second light source LD2.In this embodiment, the line pattern T1 and the speckle pattern T2 areoverlapped or not overlapped with each other, and dominant wavelengthsof the first light source LD1 and the second light source LD2 areidentical or different.

In another embodiment, the first light source LD1 and the second lightsource LD2 are turned on simultaneously. If the line pattern T1 and thespeckle pattern T2 are not overlapped with each other, a dominantwavelength of the first light source LD1 is identical to or differentfrom that of the second light source LD2 without particular limitations.However, if the line pattern T1 and the speckle pattern T2 areoverlapped with each other, the dominant wavelength of the first lightsource LD1 is preferably different from that of the second light sourceLD2 to avoid interference. In this case, the first image sensor has alight filter to block light instead of the dominant wavelength of thefirst light source LD1, and the second image sensor has a light filterto block the light instead of the dominant wavelength of the secondlight source LD2.

The processor 15 is electrically coupled to the first image sensor andthe second image sensor, and used to identify whether there is anobstacle according to the image of the line pattern T received from thefirst image sensor, and identify the appearance of the obstacleaccording to the image of the speckle pattern T2 received from thesecond image sensor.

Similarly, to reduce the power consumption and increase the accuracy,when the processor 15 identifies that there is no obstacle in a movingdirection according to the image of the line patter T1, only the firstlight source LD1 and the first image sensor are turned on, but thesecond light source LD2 and the second image sensor are not turned on asshown in FIG. 4C. The second light source LD2 and the second imagesensor are turned on only when an obstacle is detected by the processor15. When the appearance of the obstacle is depicted by the processor 15according to the image of the speckle pattern T2, the second lightsource LD2 and the second image sensor are turned off.

In another embodiment, when moving in a direction parallel to theobstacle (e.g., a wall) at a predetermined distance, the cleaning robot100 of the present disclosure captures the image of the line pattern T1using the same image sensor 13 to maintain a wall distance without usingother sensors.

For example referring to FIG. 5, it is a flow chart of an operatingmethod of a cleaning robot 100 according to one embodiment of thepresent disclosure. The operating method includes the steps of:projecting a line pattern toward a first direction when a cleaning robotmoves toward an obstacle (Step S51); calculating, by a processor, arelative distance from the obstacle according to a first image of theline pattern captured by an image sensor (Step S53); controlling, by theprocessor, the cleaning robot to turn to move parallel to the obstaclewhen the relative distance is identical to a predetermined distance(Step S55); projecting the line pattern toward a second direction whenthe cleaning robot moves parallel to the obstacle (Step S57); andmaintaining, by the processor, a parallel distance between the cleaningrobot and the obstacle to the predetermined distance according to asecond image of the line pattern captured by the image sensor (StepS59).

The operating method herein is adaptable to the above embodiments havinga single image sensor and two image sensors, respectively. Referring toFIGS. 6A-6B together, one embodiment of the operating method of thepresent disclosure is described hereinafter.

Step S51: Firstly, the cleaning robot 100 is moving toward an obstacleW1 (e.g., a wall). The first light source LD1 emits light to go throughthe first DOE 113 _(T1) to project a line pattern T1 toward a firstdirection (i.e., toward the obstacle W1). In this embodiment, it isassumed that a projected distance of the line pattern T1 is Z. The imagesensor 13 then captures a first image Im1 containing the line pattern T1as shown in FIG. 6A.

As mentioned above, when the processor 15 identifies that there is atleast one obstacle in the captured first image Im1 (the line sectiontherein being moved or broken), the operating method further includesthe steps of: controlling the second light source LD2 to emit light togo through the second DOE 113 _(T2) to project a speckle pattern T2toward the obstacle W1; and processing, by the processor 15, the imagecontaining the speckle pattern T2 to obtain two-dimensional distanceinformation, and details thereof have been illustrated above and thusare not repeated herein.

Step S53: Next, the processor 15 calculates a position (e.g., theposition H1 shown in FIG. 6A) of a line section (e.g., filled with slantline) in the first image Im1 containing the line pattern T1, andcompares the position with the information (e.g., LUT between positionsand distances) stored in the memory to obtain a relative distance fromthe obstacle W1.

Step S55: During the cleaning robot 100 moving toward the obstacle W1,the processor 15 calculates the relative distance at a predeterminedfrequency (e.g., corresponding to the image capturing frequency). Whenidentifying that the relative distance is shortened to be equal to apredetermined distance (e.g., a wall distance M which is set beforeshipment), the processor 15 controls the cleaning robot 100 to turn(left or right) the moving direction to be parallel to the obstacle W1,e.g., FIG. 6B showing a right turn being performed.

Step S57: Next, the cleaning robot 100 moves in a direction parallel tothe obstacle W1 at a predetermined distance M therefrom as shown in FIG.6B. Meanwhile, the first light source LD1 emits light to pass throughthe first DOE 113 _(T1) to project the line pattern T1 toward a seconddirection (i.e. a direction parallel to the obstacle W1) at a distanceZ.

Step S59: To maintain a parallel distance between the cleaning robot 100and the obstacle W1 to be substantially identical to the predetermineddistance M, the processor 15 continuously calculates the paralleldistance according to a second image Im2 (referring to FIG. 6B)containing the line pattern T1 captured by the image sensor 13.

In one non-limiting embodiment, the image sensor 13 includes a linearpixel array (i.e. a length thereof much larger than a width) forcapturing the second image Im2 Meanwhile, the image sensor 13 preferablyhas a wide-angle lens to allow a field of view (shown as 2θ) the imagesensor 13 to be larger than a diameter of the cleaning robot 100. Inthis way, when the cleaning robot 100 moves in a direction parallel tothe obstacle W1, the second image Im2 acquired by the image sensor 13still contains the obstacle image, e.g., the region Pn shown in FIG. 6Bindicating an image of the obstacle W1. When the cleaning robot 100moves in a direction parallel to the obstacle W1 by the predetermineddistance M, the image size (or pixel number) Pn will be substantiallyfixed, but when the parallel distance changes, the image size Pn alsochanges. Accordingly, the processor 15 further identifies whether theparallel distance is identical to the predetermined distance M accordingto the image size Pn of the obstacle W1 detected by the linear pixelarray. When the parallel distance is not equal to the predetermineddistance M, the processor 15 controls the cleaning robot 100 to adjustits moving direction to keep the predetermined distance M from theobstacle W1.

The method of controlling a moving direction of the cleaning robot 100(i.e. controlling wheels by a motor) is known to the art and not a mainobjective of the present disclosure, and thus details thereof are notdescribed herein.

In one non-limiting embodiment, the wide field of view of the imagesensor 13 is determined according to a size (e.g., diameter W) of thecleaning robot 100, a projected distance Z of the line pattern T1 and awall distance (i.e., the predetermined distance M) by triangularcalculation, e.g., θ=arctan ((M+W/2)/Z). If the size W of the cleaningrobot 100 is larger, the field of view 20 becomes larger. In addition,the processor 15 preferably has the function of distortion compensationto eliminate the image distortion caused by the wide-angle lens.

In addition, as shown in FIG. 7, as the cleaning robot 100 of thepresent disclosure adopts a wide-angle lens, compared with theconventional robot using multiple sensors, the cleaning robot 100 cansolve the problem of the existence of undetectable dead zone (e.g., FIG.7 showing the image sensor 13 detecting an object O2 at front-leftcorner which is not detectable in the conventional robot) so as toreduce the bumping of the cleaning robot 100 with obstacles to prolongthe service lifetime.

It should be mentioned that the “wall distance” mentioned in the aboveembodiments is not limited to a distance from a “wall”. The “walldistance” is a distance from any obstacle having a large area such thatthe cleaning robot 100 cleans in a direction parallel to it.

When an obstacle is transparent (e.g., a glass wall), a line pattern T1projected by a cleaning robot can penetrate the transparent obstaclesuch that the processor 15 may not identify a relative distance from thetransparent obstacle correctly. Therefore, the cleaning robot can bumpinto the transparent obstacle to generate noises and cause damage to thedevice itself or to the wall. Accordingly, the present disclosurefurther provides a cleaning robot 100′ capable of identifying a relativedistance from a transparent obstacle as shown in FIG. 8, and thecleaning robot 100′ is turned its direction when the relative distancereaches a predetermined distance.

The cleaning robot 100′ of the present disclosure includes a laser lightsource LD3, a diffractive optical element 113′, a light emitting diodeLD4, an image sensor 13 and a processor 15. In one non-limitingembodiment, the laser light source LD3 is implemented by the above firstlight source LD1, and the diffractive optical element 113′ isimplemented by the above first diffractive optical element 113 _(T1),and thus details thereof are not repeated herein. In this embodiment,the laser light source LD3 projects a line pattern T1 toward a movingdirection through the diffractive optical element 113′.

A dominant wavelength of light emitted by the light emitting diode LD4is identical to or different from a dominant wavelength of light (e.g.,850 nm to 940 nm, but not limited to) emitted by the laser light sourceLD3. The light emitting diode LD4 illuminates light with an emissionangle θ2 toward the moving direction. In one non-limiting embodiment,the laser light source LD3 projects a light pattern T1 toward the movingdirection below a horizontal direction (i.e., having a dip angle θ1)such that when there is no obstacle in front of the cleaning robot 100′,the line pattern T1 is projected on the ground on which the machine ismoving. The light emitting diode LD4 illuminates light right ahead ofthe moving direction (i.e. no deep angle or elevation angle). In someembodiments, the light emitting diode LD4 is arranged to emit lighttoward the moving direction with a deep angle or an elevation anglesmaller than 5 degrees.

The image sensor 13 is implemented by the above image sensor 13 whichacquires images with a field of view FOV toward the moving direction.Accordingly, when the laser light source LD3 is lighting, the capturedimages contain an image of the line pattern T1. As mentioned above, theprocessor 15 calculates and identifies a relative distance form anobstacle according to an image of the line pattern T1 (e.g., accordingto the position P1 mentioned above).

The processor 15 is electrically coupled to the laser light source LD3and the light emitting diode LD4 to control the laser light source LD3and the light emitting diode LD4 to emit light in a predeterminedfrequency.

As mentioned above, this embodiment is used to identify a distance froma transparent obstacle. Accordingly, when there is no transparentobstacle in a moving direction of the cleaning robot 100′, asignal-to-noise ratio (SNR) of an image (FIG. 8 showing an intensitydistribution along line A-A′) containing the line pattern T1 is within apredetermined threshold range (e.g., 50% to 70%, but not limitedthereto). However, when there is a transparent obstacle in the movingdirection of the cleaning robot 100′, the signal-to-noise ratio of theimage containing the line pattern T1 is lower than the predeterminedthreshold range. In addition, when there is a strong reflective obstaclein the moving direction of the cleaning robot 100′, it is possible thatthe SNR of the image containing the line pattern T1 is higher than thepredetermined threshold range. In this embodiment, when identifying thatthe SNR of the image containing the line pattern T1 exceeds (i.e. loweror higher than) the predetermined threshold range, the processor 15identifies a distance from the obstacle according to an area of a brightregion in the image captured when the light emitting diode LD4 islighting.

For example referring to FIG. 9, it shows a reflection image on atransparent obstacle captured by the image sensor 13 when the lightemitting diode LD4 is emitting light, wherein the captured imagecontains a bright region BA associated with the light emitting diodeLD4. It is seen from FIG. 9 that an area of the bright region BA has anopposite relationship with respect to a relative distance between thecleaning robot 100′ and the transparent obstacle, i.e. the area of thebright region BA being smaller when the relative distance is farther.Accordingly, the processor 15 identifies a distance from the transparentobstacle according to the area of the bright region BA. For example, theprocessor 15 identifies the distance according to a lookup table(recorded in a memory) of the relationship between areas andcorresponding relative distances. The bright region BA is determinedaccording to pixels having a gray value larger than a threshold in theimage.

In other words, in this embodiment, when the SNR of the image containingthe line pattern T1 is within a predetermined threshold range, theprocessor 15 calculates a relative distance from the obstacle accordingto the image captured when the laser light source LD3 is emitting light;whereas, when the SNR of the image containing the line pattern T1exceeds the predetermined threshold range, the processor 15 calculates arelative distance from the obstacle according to the image captured whenthe light emitting diode LD4 is emitting light. In one non-limitingembodiment, a dominant wavelength of light emitted by the light emittingdiode LD4 is selected to have a higher reflectivity corresponding to aspecific material (e.g., glass) to facilitate the distance detection.

Referring to FIGS. 10A and 10B, in the embodiment of FIG. 8, theprocessor 15 firstly controls, in a normal mode, the laser light sourceLD3 to emit light at a lighting frequency, and calculates a relativedistance from an obstacle according to the line pattern T1 in an imagecaptured by the image sensor 13 (arrows in FIGS. 10A and 10B referred tocapturing an image). When identifying that the SNR of the imagecontaining the line pattern T1 is within a predetermined thresholdrange, the processor 15 only turns on the laser light source LD3 withoutturning on the light emitting diode LD4. When identifying that the SNRof the image containing the line pattern T1 exceeds the predeterminedthreshold range, the processor 15 alternatively turns on the laser lightsource LD3 and the light emitting diode LD4 (as shown in FIG. 10A), oronly turns on the light emitting diode LD4 (as shown in FIG. 10B) tocalculate a relative distance from the obstacle according to an area ofthe bright region BA in the image, which does not contain the linepattern T1. The normal mode is returned to turn on the laser lightsource LD3 again till the cleaning robot 100′ turns its direction, i.e.the transparent obstacle no longer within the FOV of the image sensor13. Or, when identifying that the SNR of the image containing the linepattern T1 exceeds the predetermined threshold range, the processor 15selects to turn on the laser light source LD3 after turning on the lightemitting diode LD4 for a predetermined time interval to identify therelation between the SNR of the image containing the line pattern T1with respect to the predetermined threshold range to determine whetherto turn on the light emitting diode LD4 continuously.

In addition, the embodiment of FIG. 8 is combinable to the aboveembodiments in FIG. 2, FIGS. 6A-6B and FIG. 7 to have functions ofidentifying a transparent obstacle, constructing 2D depth informationand maintaining a wall distance. Different functions are realized aslong as the processor 15 processes images captured corresponding todifferent light sources being turned on.

As mentioned above, the conventional cleaning robot can only detectone-dimensional distance information but unable to detect the appearanceof an obstacle. Furthermore, the conventional cleaning robot usesmultiple sensors to detect a wall distance to have the problem of theexistence of dead zones. Accordingly, the present disclosure furtherprovides a cleaning robot (e.g., FIGS. 1-2) and an operating methodthereof (e.g., FIG. 5) capable of detecting two-dimensional depthinformation and calculating a wall distance using images captured by asame image sensor so as to improve the user experience.

Although the disclosure has been explained in relation to its preferredembodiment, it is not used to limit the disclosure. It is to beunderstood that many other possible modifications and variations can bemade by those skilled in the art without departing from the spirit andscope of the disclosure as hereinafter claimed.

What is claimed is:
 1. A cleaning robot, comprising: a first diffractiveoptical element; a first light source configured to project a linepattern through the first diffractive optical element; a seconddiffractive optical element; a second light source configured to projecta speckle pattern through the second diffractive optical element; and animage sensor configured to acquire an image of the line pattern and animage of the speckle pattern.
 2. The cleaning robot as claimed in claim1, wherein the line pattern is within a region of the speckle pattern.3. The cleaning robot as claimed in claim 2, wherein the first lightsource and the second light source are turned on simultaneously, and adominant wavelength of the first light source is different from that ofthe second light source.
 4. The cleaning robot as claimed in claim 2,wherein the first light source and the second light source are turned onsequentially.
 5. The cleaning robot as claimed in claim 1, wherein theline pattern is outside of a region of the speckle pattern.
 6. Thecleaning robot as claimed in claim 5, wherein the first light source andthe second light source are turned on simultaneously or sequentially. 7.The cleaning robot as claimed in claim 1, wherein a projected angle ofthe line pattern is different from that of the speckle pattern.
 8. Thecleaning robot as claimed in claim 1, further comprising a processorconfigured to identify whether there is an obstacle according to theimage of the line pattern, and identify an appearance of the obstacleaccording to the image of the speckle pattern.
 9. The cleaning robot asclaimed in claim 8, wherein the processor is configured to turn on thefirst light source but turn off the second light source when identifyingno obstacle in the image of the line pattern.
 10. The cleaning robot asclaimed in claim 8, wherein the processor is further configured toidentify a distance from the obstacle according to the image of the linepattern, and control the cleaning robot to turn to move in a directionparallel to the obstacle when the distance is identical to apredetermined distance.
 11. The cleaning robot as claimed in claim 10,wherein the image sensor comprises a linear pixel array, and when thecleaning robot is moving parallel to the obstacle, the processor isfurther configured to control the cleaning robot to maintain thepredetermined distance to move parallel to the obstacle according to animage size of the obstacle detected by the linear pixel array.
 12. Acleaning robot, comprising: a first diffractive optical element; a firstlight source configured to project a line pattern through the firstdiffractive optical element; a first image sensor configured to capturean image of the line pattern; a second diffractive optical element; asecond light source configured to project a speckle pattern through thesecond diffractive optical element; and a second image sensor configuredto capture an image of the speckle pattern.
 13. The cleaning robot asclaimed in claim 12, wherein the first light source and the second lightsource are turned on sequentially, and the line pattern is within oroutside of a region of the speckle pattern.
 14. The cleaning robot asclaimed in claim 12, wherein the first light source and the second lightsource are turned on simultaneously, the line pattern is within a regionof the speckle pattern, and a dominant wavelength of the first lightsource is different from that of the second light source.
 15. Thecleaning robot as claimed in claim 12, further comprising a processorcoupled to the first image sensor and the second image sensor, whereinthe processor is configured to identify an obstacle according to theimage of the line pattern, and identify an appearance of the obstacleaccording to the image of the speckle pattern.
 16. The cleaning robot asclaimed in claim 15, wherein the processor is further configured to turnoff the second light source and the second image sensor when no obstacleis identified in the image of the line pattern.
 17. An operating methodof a cleaning robot, the cleaning robot comprising a light source, adiffractive optical element, an image sensor and a processor, the lightsource projecting a line pattern through the diffractive opticalelement, the operating method comprising: projecting a line patterntoward a first direction when the cleaning robot moves toward anobstacle; calculating, by the processor, a relative distance from theobstacle according to a first image of the line pattern captured by theimage sensor; controlling, by the processor, the cleaning robot to turnto move parallel to the obstacle when the relative distance is identicalto a predetermined distance; projecting the line pattern toward a seconddirection when the cleaning robot moves parallel to the obstacle; andmaintaining, by the processor, a parallel distance between the cleaningrobot and the obstacle to the predetermined distance according to asecond image of the line pattern captured by the image sensor.
 18. Theoperating method as claimed in claim 17, wherein the image sensorcomprises a linear pixel array, and the operating method furthercomprises: identifying, by the processor, whether the parallel distanceis identical to the predetermined distance according to an image size ofthe obstacle detected by the linear pixel array.
 19. The operatingmethod as claimed in claim 17, wherein the image sensor has a wide-anglelens to cause a field of view of the image sensor to be larger than adiameter of the cleaning robot.
 20. The operating method as claimed inclaim 17, wherein the cleaning robot further comprises another lightsource and another diffractive optical element, and the operating methodfurther comprises: projecting, by the another light source, a specklepattern through the another diffractive optical element.
 21. A cleaningrobot, comprising: a diffractive optical element; a laser light sourceconfigured to project a line pattern toward a moving direction throughthe diffractive optical element; a light emitting diode configured toilluminate light with an emission angle toward the moving direction; animage sensor configured to acquire an image with a field of view towardthe moving direction; and a processor configured to control lighting ofthe laser light source and the light emitting diode, wherein whenidentifying that a signal-to-noise ratio of the image containing theline pattern exceeds a threshold range, the processor is configured toidentify a distance of an obstacle according to an area of a brightregion in the image which is acquired when the light emitting diode islighting.
 22. The cleaning robot as claimed in claim 21, wherein whenidentifying that the signal-to-noise ratio of the image containing theline pattern is within the threshold range, the processor is configuredto turn on the laser light source and turn off the light emitting diode.23. The cleaning robot as claimed in claim 21, wherein the laser lightsource is configured to project the line pattern toward the movingdirection with a dip angle, and the light emitting diode is configuredto illuminate the light right ahead of the moving direction.
 24. Acleaning robot, comprising: a light source module configured to providea line pattern and a speckle pattern; and an image sensor configured toacquire an image of the line pattern and an image of the specklepattern.